According to REALTOR.com. when a seller accepts an offer with a first right of refusal (FROR), the seller must notify the original interested buyer who has the right of first refusal. At that point, the person with the right of first refusal can decide whether or not to move forward with the transaction. If this first buyer declines, the seller is free to negotiate with other buyers who are interested.
Should the seller receive another offer, the first buyer either removes the first right of refusal and moves forward with the purchase OR terminates the contract.